Airplane jack

ABSTRACT

Basic unit includes first variable length column and second preferably fixed-length column pivoted together at upper ends, with load contact member at the top of one column. Bases on each column maintain the unit in upright plane. Bases pushed toward each other to initially engage load. Variable length chain holds bases at desired spacing. At least one base frictionally engages ground to prevent undesired movement. First column is extended to swing second column toward vertical and raise load. To lift airplane struts located below load contact member, cable unit is attached to load contact member and extends down to strut to lift in tension. Two basic units are connected in laterally spaced relation for two-point lifting. Third support arm may be added to provide for three-point parallelogram-type lifting of entire airplane.

United States Patent [151 3,659,824 Johnson 1 May 2, 1972 [54] AIRPLANE JACK Primary Examiner-Othell M. Simpson [72] Inventor: Philip L. Johnson, 9710 Ocean Gate, 1n-

g Calif. 9030] Attorney Forrest J. Lilly [22] Filed: Dec. 15, 1969 ABSTRACT Appl. No.: 885,244

Basic unit includes first variable length column and second preferably fixed-length column pivoted together at upper ends, with load contact member at the top of one column. Bases on each column maintain the unit in upright plane. Bases pushed toward each other to initially engage load. Variable length chain holds bases at desired spacing. At least one base frictionally engages ground to prevent undesired movement. First column is extended to swing second column toward vertical and raise load. To lift airplane struts located below load contact member, cable unit is attached to load contact member and extends down to strut to lift in tension. Two basic units are connected in laterally spaced relation for two-point lifting. Third support arm may be added to provide for three-point parallelogram-type lifting of entire airplane.

6 Claims, 8 Drawing Figures Patented May 2, 1972 3,659,824

2 Sheets-Sheet l IN VliN'lOR.

flew/ Z (Jaw/v50 Patented May 2, 1972 3,659,824

2 Shetits-Shee t 2 l/v vlw/ (m. 30 A/IMP Z. Jbmvso/v AIRPLANE JACK BACKGROUND OF THE INVENTION This invention such in the general field of mechanical lifting jacks for raising and supporting loads at predetermined levels above a supporting surface, the jacks being adapted for manual or power actuating. It is more particularly directed to a jack of sucht type which is especially suited for use with airplanes and which is relatively light, sturdy, and stable and requires minimum storage space.

In the course of performing maintenance, service, or repair work on airplanes, it is often necessary or desirable to raise all or part of the airplane above its normal ground supported level and to maintain it in raised position for some length of time. This may be done to provide convenient access to lower parts of the engine or structure or to raise one or more wheels off the ground to facilitate work on the landing gear.

An airplane of any size is normally designed to be as light as possible consistent with loading and performance requirements and its exterior surfaces are not capable of sustaining concentrated loads such as a substantial portion of the total weight of the airplane. The interior bracing structure is generally skeletal in form and hence also not suited for concentrated loads. Therefore, the structure is reinforced at a few points, usually two or three, determined to be suitable for the purpose, and jack pads are provided at these points for engagement by ground supported jacks. These jack pads may be at the undersides of the fuselage or wings, and the location and spacing between them varies widely from one make to another.

Large commercial airplanes such as those used for airline passenger or freight service are maintained in large shops usually operated by the airlines which own the airplanes. They normally have only a few types, and specific equipment is designed and provided for use with each particular type. On the other hand, the service facilities which handle small executive and pleasure-type airplanes must be able to handle a multiplicity of types with a minimum of equipment. Thus there is a need for jacking equipment which is universally usable with all of these types with equal ease so that duplication may be avoided. This equipment must be light and simple and yet extremely durable and preferably should be foldable so that it may be stowed in a small space.

SUMMARY OF THE INVENTION The present invention provides a very satisfactory answer to this need and offers a jack which is simple in construction and operation and which may be operated in substantially the same way with any type of airplane. The basic unit is used for one-point lifting, and two basic units may be combined for simultaneous two-point lifting.

Generally stated, the basic unit includes a first variablelength supporting column and a second supporting column which is preferably of fixed length but may be provided with an adjustable portion for limited extension. The two columns are pivotally connected at their upper ends to provide for variation of the included angle between them,and their lower ends are provided with bases, at least one of which is shaped to maintain the columns in a generally vertical plane. In the preferred form, each base comprises a length of pipe or rod welded or otherwise secured to the lower end of a column and extending perpendicular to the plane of the two columns. For light duty, only one of the bases may extend laterally. The upper end of one of the columns, generally the second column, is provided with a load contact member to engage the jack pad.

Quick adjustable tension means extends between the bases to retain them against separation with any desired distance between them. The presently preferred means is a length of chain with its ends connected to spaced points on one of the bases, preferably the base of the second column. An intermediate portion of the chain is loosely looped around the other column at or near its base. When the chain is fully extended in a V-shaped planform it holds the bases at such distance that the columns form an inverted V with an included angle of about although the angle is not critical. A hook is secured by its shank to one of the chain links and may be engaged with any other link to shorten the effective length of the chain and hold the columns at a more acute angle, the intermediate portion of the chain sliding around the first column as required.

Operation of the jack is normally accomplished in two phases. In the first phase the jack is located generally under the jack pad and the bases are manually moved toward each other to raise the load contact member into contact or just below the jack pad. The chain is then shortened to hold the bases at this distance. The first column is now extended and the load contact member raises the jack pad and the load to the desired level. Thus the first phase movement brings the jack into working position, and the entire extension of the first column is available for actually raising the load. The first column is in fact a jack, which may be of the screw type although a hydraulic jack is presently used because of its ease and speed for manual operation.

When only a landing gear is to be serviced it is only necessary to raise the strut sufficiently for the wheel to clear the ground. Conventional wing jacks are not adapted to lift a strut at a point near the wheel because it is too close to the ground. The present jack includes a cable member attached at the upper end to the load contact member and attachable at the lower end to the strut so that when the load contact member is raised, the cable member lifts the strut in tension.

Two basic units are used when lift is to be applied at both sides of the longitudinal centerline of the airplane. For this purpose it is preferable to connect them together, and this is accomplished with an elongate rod or pipe fitting coaxially with the bases of the first column or second column or both. For operation in unison, a cross-bar is connected to the pumping arms of both pumps, and a tie rod may also be connected to the valve operating levers of both pumps.

For three-point lifting, an elongate third-point support member is mounted on the rod or pipe joining the bases of the first columns and its upper end is provided with a third load contact member to engage a third jack pad, the third-point support member being generally parallel to the second columns. When the first columns are extended, the second columns and the third-point support member swing upwardly together in parallelogram-type fashion, raising the entire airplane.

BRIEF DESCRIPTION OF THE DRAWINGS Various other advantages and features of novelty will become apparent as the description proceeds in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view showing a pair of basic units supporting an airplane in elevated position;

FIG. 2 is a perspective view on an enlarged scale showing one basic unit in greater detail;

FIG. 3 is a perspective view showing a pair of basic units connected for operation in unison;

FIG. 4 is a partial front elevational view of the first columns and the interconnections between the pumping arms and the valve levers;

FIG. 4a is a side elevation of FIG. 4 taken along lines 4a-4a FIG. 5 is a perspective view of a basic unit and cable member for lifting a strut;

FIG. 6 is a view similar to FIG. 5, showing a modified cable member; and

FIG. 7 is a schematic view in side elevation illustrating the three-point lifting arrangement.

DESCRIPTION OF A PREFERRED EMBODIMENT The general arrangement illustrated in FIG. 1 shows a pair of basic units 10, 10 connected by a transverse spacing member 12, the upper ends of the units engaging jack pads, not shown, located on the undersides of the wings of an airplane 14 and supporting it at some desired level above the ground.

Each of the basic units is substantially identical and one of them is shown in greater detail in FlG.2 where it will be seen that the principal components are a pair of inclined supporting columns, a base for each column, and tension means to hold the bases against separation. The first supporting column 16 is of variable length and may be a screw jack but is preferably a hydraulic jack having a cylinder 18, a piston, not shown, and a piston rod 20 connected to the piston and extensible through the upper end of the cylinder. The second supporting column 22 is preferably of fixed length and is provided at its upper end with a clevis 24, to which the upper end of piston rod 20 is connected by a pivot pin 26 to provide for variation of the included angle between columns 16 and 22.

Each column is provided FlG.4, a base for engagement with the ground or other supporting surface. For simplicity and maximum stability, the bases in the preferred form comprise metallic tubes 28 and 30, each rigidly secured to the bottom of its respective column by welding or other suitable: means. In the case of column 16 and referring to FIG. 4 cylinder 18 has a bottom flange 32 which may be bolted or welded to flange 34 on bracket 36 which is welded to base pipe 28. The re-entrant curve between flange 34 and pipe 28 provides a seat for sliding engagement with a length of chain.

Column 22 is directly welded to pipe at 38 and is preferably provided with a single diagonal brace rod 40 welded to one end of pipe 30 and to the upper end of column 22. As shown in FlG.2, the rod passes through column 22 and its upper end 42 is curved to constitute a load contact member. If desired, the brace rod may terminate at its junction with the column, and member 42 may be attached to the upper end of either column. In a modification, member 42 may be mounted on a shank of any length fitted into the upper end of column 22 and either fixed or extensible to vary the initial height of the jack between predetermined reasonable limits.

The jack is shown in FIG.2 at its predetermined minimum height which is so selected that member 42 can be located at least slightly below the lowest jack pad likely to be encountered. It is retained in this position by suitable quick adjustable tension means such as chain 44 which is connected at its ends to brackets 46 secured to base 30 at spaced points preferably near the ends of the base. An intermediate portion of the chain passes around cylinder 18, or more specifically bracket 36, in the re-entrant portion between flange 34 and base 28 and thus the chain acts to prevent separation of the bases. A hook 48 is secured to one of the links and may engage any other link to reduce the effective length of the chain with the intermediate portion sliding around bracket 36.

The bases are preferably devoid of wheels so that their frictional contact with the ground will prevent any unintentional movement relative to the ground when the jack is under load. However, the unit is light enough to be easily slid along when it is unloaded. In operation, the jack is moved to a position where member 42 is under the intended jack pad and the bases are manually pushed toward each other until member 42 rises to a position substantially in contact with the jack pad. The chain is then shortened and hook 48 is engaged with an appropriate link to prevent separation of the bases. Since members 18 and 20 are relatively rotatable, bases 28 and 30 may be rotated through slight angles in the ground plane to accommodate themselves to uneven surfaces. Column 16 is now extended by operating pumpingarm 50 by handle 52, the arm being connected to pump 54 on cylinder 18 by a bracket 56, link 58 and piston rod 60 which are of known construction. Extension of column 16 swings column 22 upward and clockwise as viewed in F162, and member 42 raises the load to the desired level.

Lateral stability is provided by the extension of bases 28 and 30 to both sides of the vertical plane containing columns 16 and 22. While one base, such as 28, might have little or no lateral extension and still provide tripod-type stability, it is preferred to make the bases as shown and obtain maximum stability. Fore and aft stability is provided by insuring that the load contact member 42 is always over a locus between the two bases under all conditions. For this purpose, extensible column 16 has a minimum length considerably less than the length of column 22, and a maximum length which is not substantially greater than the length of column 22. Thus, the extending action will have a large vertical component and column 22 will not swing close enough to vertical to cause instability.

For two-point lifting such as indicated in FIG.1, a pair of basic units are secured together as shown in FIGS. Transverse spacing member 12 may be a bar or tube which slidingly fits within the adjacent ends of bases 30 to make a continuous straight base. Detents 62 are provided on member 12 to define the desired spacing. They may be simple welded abutments or bolts insertable in selected holes along the length of member 12 to define the proper spacing for various types of airplanes.

In many cases a second similar spacing member 64, having detents 66, may connect bases 28 in the same way. Member 64 may further be provided with a bracket or clevis 68 to which the lower end of a third-point support member 70 is pivotally connected by pivot pin 72 for lateral swinging. Member 64 is rotatable about its coincident axis with bases 28. The upper end of member 70 is provided with a third load contact member 74. With this arrangement, three-point lifting may be accomplished as illustrated schematically in F167 Member 70 is preferably about the same length as member 22 although it may be somewhat shorter or longer and still function effectively. As seen in FlG.7, member 70 is initially at about the same angle as the two columns 22. When column 16 is extended, columns 22 swing to the broken line position, carrying load 76 to its broken line position. Since member 74 is in contact with the third jack pad, member 70 swings to its broken line position to accomplish parallelogram-type lifting. The pivotal mounting at 72 allows member 70 to swing laterally to a slight extent to allow for slight lateral shifting of the load as it rises.

Returning to F IGS.3 and 4, it will be seen that means are provided for actuating the two variable-length columns in unison. Each of the pumping arms 50 is provided with a socket 76 to receive handle 52. For dual operation handles 52 are removed and replaced by a horizontal cross-bar 78 having laterally bent end portions 80 which are fitted into the sockets. The cross-bar may be grasped at an intermediate point and raised and lowered to swing pumping arms 50 to the same extent and at the same time so that the load will be raised uniformly.

Release valves 82 are provided to allow return flow of the pumping fluid and they are provided with valve operating levers 84. A tie rod 86 is provided which attaches at its ends to the levers and is moved laterally to swing them in unison. Since the levers may not occupy exactly the same angular position when the valves are fully closed, one of them is provided with an adjustment means. As shown at the right in FIG.4, lever 84 is provided with an adjustment plate 88 swingable on the pivotal axis of the lever. The plate is formed with an arcuate slot 90 to receive a stud 92 projecting from the lever and a nut 94 on the stud locks the plate to the lever in any relative angular position. The upper end of the left lever 84 and the upper end of plate 88 are provided with pivot pins 96 on which the ends of tie rod 86 are mounted to move them in unison.

It was mentioned earlier that only one brace rod 40 is provided for column 22. This allows the two columns which are in a vertical plane to be placed close to a landing gear wheel of a light airplane having diagonal landing gear struts as indicated in E1685 and 6. When servicing is to be performed only on the wheel, brake, or axle, it is preferable to apply lift forces at the lower end of the strut but the usual wing and fuselage jacks are too high to be used for this purpose. Some automobiletype jacks can be used but they have small bases and are so unstable that it is too dangerous to use them.

The present jack is admirably suited for this purpose. It is placed in position as shown in FlG.5 by disconnecting the loop of chain 44 from base 28, erecting the columns inboard of the wheel 100 and above strut 98, passing the chain under the strut, and then again looping the chain around the column at base 28. The jack may then be moved quite close to the wheel and the fairing 102 because of the absence of a diagonal strut on one side. A U-shaped saddle 104 having flanges 106 is placed under the leaf-spring-type tapered strut 98 and moved upward into wedging engagement. A T-bar 108 is then inserted in holes 110 in the flanges to provide a lifting attachment. Cable 112 is connected at its lower end to the T-bar and at its upper end is provided with an eye 114 which is fitted over member 42, the latter now serving as a hook. Raising member 42 in the manner previously described applies tension to cable 112 and raises the wheel above the ground. Because of the extent of bases 28 and the support is extremely stable and therefore safe.

A modified tension means is used in the case of a tubulartype strut 116 as shown in FlG.6. An axle member 118 extending from the lower end of the strut is secured thereto by bolts 120 and at its outer end carries a wheel 122 covered by a fairing 124. The jack is positioned in the same way as described above. In this case a cable 126 is provided, having eyes 128 at each end. The intermediate portion is looped around the lower end of the strut between bolts 120 and the eyes 128 are fitted over member 42. When the latter is raised, tension in the cable will raise the strut. The bolts 120 act as abutments to prevent the cable from slipping up the length of the strut.

It will be apparent that the present invention provides a jack intended primarily for airplane use but suitable for lifting many different types of loads, which is light but strong and easy to use. Because of the pivotal connection of the columns and the flexibility and releasability of the chain, the entire unit can be folded into a substantially flat and compact bundle for easy storage and may be readily carried in an airplane if necessary. The basic units may be used singly or in pairs to provide one, two, or three point support and the design may be readily modified for use with high-wing airplanes by mounting the first column on an extension member and elongating the second column by a corresponding amount. Its extreme versatility makes it suitable for all lifting needs of any type of noncommercial airplane.

I claim:

1. A foldable jack for lifting and supporting a load at a desired level above a supporting surface, comprising:

a first, elongate, variable-length supporting column having a base at one end for engagement with a supporting surface;

a second, elongate supporting column having a base at one end for engagement with a supporting surface;

the ends of said solumns opposite said bases being pivotally connected to provide for variation of the included angle between them;

the bases being shaped to maintain the connected columns in a generally vertical plane with their pivotal connection spaced above the supporting surface and over a locus between the bases;

a load contact member mounted at the upper end of one of said columns;

said bases being manually movable toward each other to reduce the included angle and raise the load contact member to a point adjacent to the load to be lifted;

quick-adjustable tension means extending between said bases to prevent undesired separation;

means to increase the length of said first column to cause said load contact member to rise and lift the load to the desired level; and

means to engage and lift a load located well below the level of said load contact member including elongate force transfer means adapted to be connected in generally ver- LII tical relation between the load and the load contact member and to transmit the lifting force of the latter to the fonner.

2. A jack as claimed in claim 1 wherein said force transfer means comprises a U-shaped saddle to underlie an airplane landing gear strut; and

a length of flexible cable having means at one end for attachment to the saddle and means at the other end for attachment to said load contact member.

3. A jack as claimed in claim 1 wherein said force transfer means comprises a length of flexible cable adapted to be looped at an intermediate point around an airplane landing gear strut; and

means at each end of said cable for attachment to said load contact member.

4. A foldable jack for lifting and supporting a load at a desired level above a supporting surface, comprising:

a first, elongate, variable-length supporting column having a base at one end for engagement with a supporting surface;

a second, elongate supporting column having a base at one end for engagement with a supporting surface;

the ends of said columns opposite said bases being pivotally connected to provide for variation of the included angle between them;

the bases being shaped to maintain the connected columns in a generally vertical plane with their pivotal connection spaced above the supporting surface and over a locus between the bases;

a load contact member mounted at the upper end of one of said columns;

said bases being manually movable toward each other to reduce the included angle and raise the load contact member to a point adjacent to the load to be lifted;

quick-adjustable tension means extending between said bases to prevent undesired separation;

a second pair of supporting columns and bases provided with tension means substantially similar to said first columns, bases, and tension means;

releasable means connecting the two sets in predetermined space relation with the vertical plane containing the first pair of columns parallel to and spaced from the vertical plane containing the second pair of columns to operate as a unit supporting a common load at two spaced points;

each of said first columns comprising a hydraulic cylinder and extensible piston rod;

a pump mounted on each cylinder and including a pumping arm; and

a cross-bar connected to both of said pumping arms to actuate them in unison.

5. A jack as claimed in claim 4 including a release valve mounted on each cylinder and including a valve operating lever; and

a tie rod connected to both of said levers to operate them in unison.

6. A jack as claimed in claim 1 including a second pair of supporting columns and bases provided with tension means substantially similar to said first columns, bases, and tension means;

releasable means connecting the twosets in predetermined space relation with the vertical plane containing the first pair of columns parallel to and spaced from the vertical plane containing the second pair of columns to operate as a unit supporting a common load at two spaced points;

said bases of said first columns comprising elongate members arranged in coaxial relation;

said releasable means including an elongate spacer member coaxial with said base members and connected therewith for rotation about their common axis;

an elongate third-point support member secured at its lower end to said spacer member and provided at its upper end with a third load contact member;

said third-point support member is of substantially the same length as each of said second columns to provide a para]- lelogram relationship for lifting the load without tilting; and

said third-point support member is pivotally connected to said spacer member for lateral swinging to allow its third load contact member to accommodate lateral shifting of the load at the point of contact. 

1. A foldable jack for lifting and supporting a load at a desired level above a supporting surface, comprising: a first, elongate, variable-length supporting column having a base at one end for engagement with a supporting surface; a second, elongate supporting column having a base at one end for engagement with a supporting surface; the ends of said solumns opposite said bases being pivotally connected to provide for variation of the included angle between them; the bases being shaped to maintain the connected columns in a generally vertical plane with their pivotal connection spaced above the supporting surface and over a locus between the bases; a load contact member mounted at the upper end of one of said columns; said bases being manually movable toward each other to reduce the included angle and raise the load contact member to a point adjacent to the load to be lifted; quick-adjustable tension means extending between said bases to prevent undesired separation; means to increase the length of said first column to cause said load contact member to rise and lift the load to the desired level; and means to engage and lift a load located well below the level of said load contact member including elongate force transfer means adapted to be connected in generally vertical relation between the load and the load contact member and to transmit the lifting force of the latter to the former.
 2. A jack as claimed in claim 1 wherein said force transfer means comprises a U-shaped saddle to underlie an airplane landing gear strut; and a length of flexible cable having means at one end for attachment to the saddle and means at the other end for attachment to said load contact member.
 3. A jack as claimed in claim 1 wherein said force transfer means comprises a length of flexible cable adapted to be looped at an intermediate point around an airplane landing gear strut; and means at each end of said cable for attachment to said load contact member.
 4. A foldable jack for lifting and supporting a load at a desired level above a supporting surface, comprising: a first, elongate, variable-length supporting column having a base at one end for engagement with a supporting surface; a second, elongate supporting column having a base at one end for engagement with a supporting surface; the ends of said columns opposite said bases being pivotally connected to provide for variation of the included angle between them; the bases being shaped to maintain the connected columns in a generally vertical plane with their pivotal connection spaced above the supporting surface and over a locus between the bases; a load contact member mounted at the upper end of one of said columns; said bases being manually movable toward each other to reduce the included angle and raise the load contact member to a point adjacent to the load to be lifted; quick-adjustable tension means extending between said bases to prevent undesired separation; a second pair of supporting columns and bases provided with tension means substantially similar to said first columns, bases, and tension means; releasable means connecting the two sets in predetermined space relation with the vertical plane containing the first pair of columns parallel to and spaced from the vertical plane containing the second pair of columns to operate as a unit supporting a common load at two spaced points; each of said first columns comprising a hydraulic cylinder and extensible piston rod; a pump mounted on each cylinder and including a pumping arm; and a cross-bar coNnected to both of said pumping arms to actuate them in unison.
 5. A jack as claimed in claim 4 including a release valve mounted on each cylinder and including a valve operating lever; and a tie rod connected to both of said levers to operate them in unison.
 6. A jack as claimed in claim 1 including a second pair of supporting columns and bases provided with tension means substantially similar to said first columns, bases, and tension means; releasable means connecting the two sets in predetermined space relation with the vertical plane containing the first pair of columns parallel to and spaced from the vertical plane containing the second pair of columns to operate as a unit supporting a common load at two spaced points; said bases of said first columns comprising elongate members arranged in coaxial relation; said releasable means including an elongate spacer member coaxial with said base members and connected therewith for rotation about their common axis; an elongate third-point support member secured at its lower end to said spacer member and provided at its upper end with a third load contact member; said third-point support member is of substantially the same length as each of said second columns to provide a parallelogram relationship for lifting the load without tilting; and said third-point support member is pivotally connected to said spacer member for lateral swinging to allow its third load contact member to accommodate lateral shifting of the load at the point of contact. 